Apparatus for carrying out reactions continuously in the liquid phase under increased pressure



Oct. 25, 1932. SAUNDERS 1,884,880 APPARATUS FOR CARRYING OUT REACTIONS CONTINUOUSLY IN THE LIQUID PHASE UNDER INCREASED PRESSURE Filed May 18, 1929 A/ENNETH HEEEE/ET Snwv0E/es,

Patented Oct. 25, 1932 UNITED STATES .KENNETH HERBERT SAUNDERS, OF BLACKLEY, MANCHESTER, ENGLAND, ASSIGNOR TO IMPERIAL CHEMICAL INDUSTRIES LIMITED, OF LONDON, ENGLAND APPARATUS FOR CARRYING OUT REACTIONS GONTINUOUSLY IN THE LIQUID PHASE UNDER INCREASED PRESSURE Application filed May 18, 1929. Serial No. 364,153.

In my co-pending application Serial'No. 315,906 I have disclosed a form of apparatus suitable for carrying out in a continuous manner reactions which occur in the liquid phase at an elevated temperature under the vapour pressure of one or more of the components. This apparatus was an improvement over the apparatus involving coiled pipes usually proposed for such purposes and its technical advantage lies in the fact that by its use it is possible to dispense with a hydraulic accumulator as a means of keeping steady the working pressure, while at the same time allowing for fluctuations in the volume of the liquid passing through the apparatus, hereafter referred to as the converter.

The present invention is concerned with certain advantages! which reside in some modifications of the form of apparatus which has been described in the above mentioned application, devised as a result of my experiments with this converter for the manufacture of p-nitroaniline from p-chlorouitrobenzene and aqueous ammonia (although the converter is not by any means limited in its application to this particular reaction). When performing this operation, I have found that in time corrosion is liable to be produced in those iron and steel parts of the converter which come in contact with the ammonia stream carrying the p-cl1loroni trobenzene and p-nitroaniline in solution. It is possible that this corrosion is caused by ammonium chloride in spite of the presence of an excess of ammonia. The corrosion shows itself by pitting of the upper parts of the pressure-sustaining Walls of the converter together with the upper part of the outside and the inner side of the central tube. The ordinary grades of steel suitable for the construction of the pressure-sustaining walls of the converter are liable to attack by so strongly corrosive a liquid as hot aqueous ammonium chloride while alloys and other metals known to resist are both costly and of unsuitable mechanical properties.

It is obvious that there would be diificulties in surmounting this corrosion hazard when working with coils since inspection of their interior is naturally impossible and even if they are periodically replaced an element of danger must always attend their use. My converter provides a remedy for this unsatisfactory state of affairs by slight alterations in the construction of the interior. In my modified converter the incoming am.'- monia stream only is in contact with the pressure-sustaining walls and I construct those remaining parts which are still liable to corrosive attack, of stainless steel or of enamelled steel or in short of any suitable anti-corrosive material. In the accompanying illustration I have shown, more or less diagrammatically, an embodiment of my invention useful in the performance of the described process. In this showing the figure is a view in vertical section with certain parts in elevation.

Referring to the structure shown in Fig. 1, element A is a vertical cylinder capable of withstanding a high pressure and closed top and bottom in any suitable manner, for instance, by lens ring joints as shown. The converter is heated in any suitable manner to 200250 C. Preheated ammonia liquor enters by the side arm B and is distributed in the space D by the distributor ring C. It is there constrained by the stainless steel or other anti-corrosive mantle or sheath E to flow downwards over the whole length of the pressure-sustaining walls until it arrives in the space F. From here it passes upwards in the annulus between the mantle E and the stainless steel central tube Gr. Low down in the annulus is a cage I-I, containing packing material or plates I. The upflowing ammonia passes through the perforated bottom of the cage and meets in the packing a falling stream of melted p-chloronitrobenzene. The latter is preheated and forced in by the tube J, eventually flowing out into the distributor plate K, from which it overflows by a series of holes on to the packing I., For each litre of .880 ammonia liquor I force in 150 to 200 rms. of molten p-chloronitrobenzen-e at 225 a The solution in the hot ammonia stream is rapid and the reaction to form p-nitroani line and ammonium chloride takes place in the period of time necessary for a given particle in the ammonia stream to travel upwards from the distributor plate and overflow into the central tube G, from the bottom of which the solution is drawn oil by the valve L. I commonly employ a contact time of to 40 minutes for the reaction. It will thus be seen that the corrosive solution is at all times 7 constrained in a space between wallsof stain-. less'steel or other anti corrosivematerial of which the pyrometer sheath O is also constructed. -Moreover, it is easy at any time to V dismantle the whole converter and examine the interior for signs of corrosion. The pressure in the converter is given by the gauge M which in this construction is protected from blockage by crystals or corrosion. The valve N is used only in emergency to blow down the contents of theannulus.

'WhatI claim andfldesire to secure by Lette'rs Patent is r V 1. In an apparatus for carrying out reactions continuously under pressure, an outer pressure retaining cylinder closed at both ends, a shorter mantle withinsaid cylinder closed supported at its upper end and leaving an annular space between said outer -cylinder and said mantle, fluid distributing means within said annular space, astill shorter inner cylinder supported from its lower end and leaving an annular-chamber between said 'mantle and said innercylinder, packing within said annularchamber at its lower end,

fluid distributing means above said packing,

, and fluid rdraw-ofli means at the bottom of said inner cylinder. g

2. In an apparatus for carrying out reactions continuously at high pressures, an outer pressure retaining structure, closed-at both ends, a looselyfitting mantle supported at the 40 top within said outer'structure, liquid distributing means at the upper end of said mantle and between said 'outer cylin der and said mantle, a reaction chamber Within said man'- tle, fluid distributing means within said reaction chamber and overflow means within said reaction chamber for the reaction prodnets of said liquid and said fluid.

The apparatus of claim 2 wh-ereinf the said mantle and the'said overflow means are 5 constructed of corrosion resistant material,

while the outer pressure retaining structure is constructed'ofsteel. I 4. The apparatus of claim 1 in which the saidnmantle and the saidinner cylinder are constructed of corrosion resistant material.

- In testimony whereof I aifix my signature.

.; KENNETH HERBERT SAUNDERS. 

